In the field of printing, the most common type of printer has been the printer which impacts against record media that is caused to be moved past a printing line or line of printing. As is well-known, the impact printing operation depends upon the movement of impact members, such as print hammers or wires or the like, which are typically moved by means of an electromechanical system and which system enables precise control of the impact members.
In the field of dot matrix printers, it has been quite common to provide a print head which has included therein a plurality of print wire actuators or solenoids arranged or grouped in a manner to drive the respective print wires a precise distance from a rest or non-printing position to an impact or printing position. The print wires are generally either secured to or engaged by the solenoid plunger or armature which is caused to be moved such precise distance when the solenoid coil is energized and wherein the plunger normally operates against the action of a return spring.
In the wire matrix printer, the print head structure may be a multiple-element type with the wire elements aligned in a vertical line and supported on a print head carriage which is caused to be moved or driven in a horizontal direction for printing in line manner, while the drive elements or transducers may be positioned in a circular configuration with the respective wires leading to the front tip of the print head.
Alternatively, the printer structure may include a plurality of equally-spaced, horizontally-aligned single-element print heads which are caused to be moved in back-and-forth manner to print successive lines of dots in making up the lines of characters. In this latter arrangement, the drive elements or transducers are individually supported along a line of printing. These single wire actuators or solenoids are generally tubular or cylindrically shaped and include a shell which encloses a coil, an armature and a resilient member arranged in manner and form wherein the actuator is operable to cause the print wire to be axially moved a small precise distance in dot matrix printing. The print wire is contained and guided at the front of the solenoids in axial direction during the printing operation.
Representative documentation in the field of dot matrix print head wire guide means includes U.S. Pat. No. 3,467,232, issued to W. G. Paige on Sept. 16, 1969, which discloses an end cap made of Teflon or another low friction material.
U.S. Pat. No. 3,782,520, issued to R. Howard on Jan. 1, 1974, discloses a jewel bearing press fitted into a recess of a guide tube and swaged over the end to retain the jewel.
U.S. Pat. No. 3,907,092, issued to O. Kwan on Sept. 23, 1975, discloses a jewel in the front of the print head with print wire openings in the jewel.
U.S. Pat. No. 4,154,541, issued to T. Tsukada on May 15, 1979, discloses a lip guide formed from a jewel member fixed to the forward end of the print head.
U.S. Pat. No. 4,365,902, issued to H. H. Biederman on Dec. 28, 1982, discloses wire guides made from a ruby rod placed into a recess at the front of the print head and cemented in the recess.
And, U.S. Pat. No. 4,447,166, issued to K. Ochiai on May 8, 1984, discloses an artificial ruby or sapphire or aluminum oxide needle guide received or inserted into the front portion of a guide holder of the print head.